Internal combustion engine with adjustable pressure



May 9, 1939.

R. GEISSLINGER El AL INTERNAL COMBUSTION ENGINE WITH ADJUSTABLE PRESSURE Filed Aug. so, 1935 Patented May 9, 1939 PATENT OFFICE INTERNAL COMBUSTION ENGINE WITH ADJUSTABLE PRESSURE tRobert Geisslinger and Kurt Reinhold Greiner,

' Vienna, Austria Application August 30, 1935, Serial No. 38,62

In Austria September 19, 1934 4 Claims.

This invention relates to internal combustion engines. The invention consists in the arrangement whereby one and the same movable wall member or auxiliary piston arranged in the 5 combustion chamber, or in a chamber communicating therewith, is so loaded by two counter-balancing resilient means of different magnitudes, comprising gaseous pressures, that the smaller resilient pressure is overcome by the compression pressure and the greater resilient pressure by the higher combustion or explosion pressure in the combustion chamber, and the wall member or auxiliary piston is moved backward as each of these counteracting forces is overcome. The result is thereby obtained that during the first backward movement the compression pressure is kept constant, independently of the particular amount of the charge admitted to the engine, and by the second backward movement of the wall member 20 or auxiliary piston, potential energy is stored up in the latter in a well known manner, which, during the following drop in pressure in the combustion chamber, is given back again in the performance of work.

25 By the selection of counteracting resilient means of different moduli acting on one or more wall members, such as mostly correspond to the substantially difierent pressures during the compression and working stroke, it is possible to pro- 30 vide, for the two strokes, definite and completely separate conditions adapted to them, which can easily be predetermined and controlled in their effects and can also be easily controlled in furlowest position, which is determined for instance ther sequence by regulation.

35 The resilient walls may be formed by pistons, diaphragms or the like, and in special forms of construction by the main piston or working cylinder itself.

A form of construction of the machine is pref- Li) erable which is characterised by two or more wall members or pistons, which are arranged in the combustion space or in a space communicating with it, and which are so loaded by gaseous pressures of difierent moduli that one or more pisl tons are movedbackward by the compression pressure and one or more pistons by the working pressure.

If the counter-loadings of different .noduli or the length of the movements of the wall members desired higher pressure prevails.

conditions that are most suitable in practice can be provided.

The pressure conditions can be regulated by adjusting the counterbalancing resilient means acting upon the wallmembers or pistons and the 5 sizes of the clearance space and of the compression space can be regulated by adjusting the length of the movements of the wall members.

Two examples of construction of the invention are diagrammatically illustrated in axial section in Figures 1 and 2 of the accompanying drawing.

In the constructional example of Figure l, which relates to an engine working on the fourstroke cycle for instance, I is the working piston, and 2 an auxiliary piston which is subject to a gaseous pressure prevailing in the space 3, this space 3 being enclosed by the auxiliary piston 2 and a second auxiliary piston 2' located above it, above which, in the space 4, a greater gaseous pressure is maintained than in the space 3. The space 3 is in constant communication through an opening it with a large space (not shown) in which the pressure, (gas or air), is maintained at the desired height. The space 4 is in constant communication through openings H and H with a second large space (not shown) in which the The pressures, which are concerned as counter-pressures to the pressure prevailing in the interior of the working cylinder, are thereby maintained at practically constant heights. Under the influence of these two-pressures the auxiliary piston 2 assumes its by a rod 6 connected with the auxiliary piston and guided at 5, together with a nut I screwed on to it. By screwing this nut up and down the lowest position of the auxiliary piston 2- can be altered. For the auxiliary piston 2 a limitation of stroke is preferably provided. This consists, in the example illustrated, of a screw H with a stop I8 for the rod 6. To the auxiliary piston 2 is given a certain amount of clearance 6' in relation to the rod 6.

This device works in the following manner: 5 When the working piston l moves upwards, with the exhaust valve opened, it expels the burnt gases until it almost touches at the upper dead centre, the auxiliary piston 2, which, in consequence of the resilient pressure thereon, is occupying its lowest position. Since the clearance space, at least between the working piston I and the auxiliary piston 2, is thereby reduced to a minimum,

the expulsion of the combustion gases takes place The ensuing suction of the mixture of fuel and air is greatly improved With espect to quantity inder increases until it corresponds approximately to the pressure in the space 3 whereupon the auxiliary piston 2 is eventually pressed backward until the completition of the stroke ofthe working piston I, whereby the compression pressure is not further increased. The size of the compression. space between pistons l and 2, and therefore the modulus of the compression pressure, is thereby determined from the outset at each compression stroke independently of the amount of charge admitted to the main cylinder.

' Upon explosion of the charge the pressure between the two pistons l and 2 rises so powerfully and suddenly that the auxiliary piston 2 is pushed backward, overcoming even the rather high gase'.

ous pressure in the space 4, and thereby stores up potential energy, and provides an enlarged working space and a correspondingly diminished maximum pressure, which corresponds substantially to the gaseous pressure in the space 4. In the succeeding working stroke of the cycle the auxiliary piston 2 gives up the stored potential energy again with performanceof work, in that it follows up the working piston I right to the end of its stroke, and thereby maintains the working space and the working pressure, during a portion of the stroke of the working piston, approximately at the same magnitude. Hence instead of a rather high and rapidly diminishing pressure in the main cylinder, a lower pressure exists, which remains about the same during a portion of the piston stroke. The indicator diagram will accordingly no longer exhibit theundesirable peak;

this is replaced by a line extending for a certain distance approximately parallel to the axis of the abscissae, thereby attaining an approximation to the constant-pressure diagram of 3. Diesel engine or else to a steam-engine diagram. The expansion of the combustion gases thereby comes into action later.

By selecting difierent gaseous pressures in the space 3 and difierent gaseous pressures in the space 4, both the working pressure and the compression pressure can be controlled.

The aggregate advantages thus associated are as follows: Attainment of a more uniform torque on the crank, elimination of the knocking of the motor and better utilization of fuel. This arises from the fact that the maximum working pressure, instead of being operative only for a short time in an unfavourable crank position is operative for a longer time with a more favourable crank position. Furthermore, in consequence of diminution of the maximum pressures, less heat is imparted to the device and hence not so much heat has to be removed by cooling as hitherto; thus the thermal efiiciency of the motor is also improved. Moreover, in consequence of the elimination of excessive combustion pressures and temperatures, greater durability and greater elasticity of the motor are attained. Owing to the diminution in the maximum pressure it is easier to keep the cylinder, piston and so forth fluidtight, the corresponding constructional parts may be of lighter dimensions, their inertia is reduced, anda cheaper construction becomes possible. The relationship between speed of revolution and power output of the motor is advantageously influenced as shown by the more favorable diagram; it therefore has a better output even at a rather low speed, thus improving the. hill-climbing properties of motor vehicles. Lower speeds may be maintained without the occurrence of knocking. Owing to the improved quantity and quality of the charge, higher speeds of revolution are also attainable without a compressor, thereby saving energy. By the more uni form stressing of the machine parts the risk of breakage is diminished.

With this constructional example the piston strokes in both directions can be regulated.

Figure 2 shows the advantageous employment of two pistons, namely a relatively large counterpiston 2 in the working cylinder and a smaller counter-piston ll in a special cylinder l5. Both pistons are subject on their outer sides to the pressure of a gas: the piston 2 to a high pressure and the piston H to a low pressure. Similarly as in Figure 1, the space 3' above the piston I4 is in constant communication through opening ID with a large space in which the desired pressure prevails while the space 4' above the piston 2 is in constant communication through openings I I, I2 with'a second large space in which the desired higher pressure prevails. By 8 and 9 are denoted the suction valve and the exhaust valve respectively, and I6 is the sparking plug. 8' and 9' respectively designate ports of admission and exhaust for the valves 8 and 9.

With this arrangement the small piston ll serves for adjusting the compression pressure, and the larger piston 2 for adjusting the maximum working pressure. Both the pistons are adjustable, both in respect to loading and in respect to length of travel, the piston strokes in this constructional example being adjustable in one direction only.

What we claim is:

1. In an internal combustion engine in combination with the working chamber of the cylinder and the working piston, two movable walls of which at least one closes the said working chamber, means to keep these walls on their side remote from the working chamber of the cylinder under practically constant pressure of a medium of pressure which is opposing the pressure within the said working chamber, said pressures being of a different force, the wall subjected to the lower counter-acting pressure being moved backward by the compression pressure -within the cylinder, whereby the compression pressure is being kept constant regardless of the amount of the charge, the other wall being exposed to the higher counter-pressure will be moved backward only by the higher combustion pressure, whereby potential energy is stored posed to the higher counter-pressure will be turned tothe working piston.

2. In an internal combustion. engine in combination with the working chamber of the cylinder and the working piston a movable wall which closes the working cylinder, means exposing the said movable wall on its side remote from the working chamber of the cylinder to a practically constant counter-pressure of a medium of pressure which counter-acts the pressure within the working cylinder, 9. second movable wall, arranged behind the first mentioned wall, means connecting said movable wall members, said means allowing limited relative movement be.- tween same. means exposing this wall on its backside to a practically constant, but higher than the aforementioned pressure, of a medium of pressure counter-acting the pressure within the said working chamber, the first mentioned wall being moved backward by the compression pressure whereby the compression pressure is being kept constant, regardless of the amount of the charge, the second wall will be moved backward only by the higher combustion pressure, whereby potential energy is stored, which during the expansion stroke, will be returned to the working piston.

3. An internal combustion engine according to claim 1, provided with means suitable to adjust the stroke of the two movable walls in the direction toward, the working piston.

4. In an internal combustion engine, a working cylinder, a working piston and a plurality of auxiliafy pistons in said cylinder, said pistons dividing said cylinder into a combustion chamher and fluid pressure chambers, means for maintaining fluid pressure in said fluid pressure chambers, the pressure maintained in the chamber adjoining the combustion chamber being less than that of compression in the combustion chamber and the pressure in the next adjoining chamber being greater than the maximum compression pressure but less than the combustion pressure, means connecting said auxiliary pistons, said means allowing limited relative movement between said auxiliary pistons whereby the exhaust gases are more completely expelled and the energy of the combustion is more gradually applied to the working piston,

- ROBERT GEISSLJNGER.

KURT REINHOLD GREINER. 

